In a wireless communication network, scheduling is an effective way to improve the quality of service (QoS: Quality of Service) of communications. “Scheduling” refers to scheduling of a transmission time to which data to be transmitted from a wireless station to a base station should be allocated, and the scheduling is performed by a base station. Here, a base station is an AP (access point) in the case of microwave communications, and a PCP (Personal basic service set Control Point) in the case of millimeter-wave communications. Then, when receiving a transmission request from a wireless station (STA), an access point or a PCP schedules a dedicated transmission time period for a specified traffic stream, which is data to be transmitted by the wireless station. Note that, in the following description, scheduling of a dedicated transmission time period is also called “bandwidth allocation”. Since we can avoid contention that may occur when a wireless channel, or in other words, a wireless communication resource is accessed, utilization ratio of the wireless channel is increased by performing scheduling. An access point or a PCP broadcasts a “schedule”, which is a result of scheduling, to all wireless stations using a beacon frame. Each wireless station transmits the specified traffic stream in accordance with the broadcast schedule.
In the case where a wireless channel is used for transmission of a traffic stream having a real-time requirement, such as video streaming, efficient bandwidth allocation through advanced scheduling is desired. For example, in order to ensure the real-time requirement, it is necessary to periodically allocate transmission time periods to a wireless channel. In addition, in order to transmit all data inputted in each period, it is necessary to calculate, for each traffic stream, a transmission time period to be allocated to the traffic stream in accordance with the amount of data of the traffic stream. PTL 1 discloses a scheduling method for a plurality of traffic streams having real-time requirements in microwave communications based on, for example, IEEE Std 802.11e. In the scheduling method described in PTL 1, the same interval (so-called “service interval: Service Interval (SI)”) is allocated to a plurality of traffic streams. Such a method is effective in microwave communications.